Spring sash balance



y 7, 1953 i A. W.YANDE.RBERG 2,644,193

SPRING SASH BALANCE 2 Sheets-Sheet 1 Filed Nov. 17, 1950 I INVENTOR. 8w 5 Y- ATZ'ZRMEYSO July 7, 1953 A. w. ANDERBERG 2,644,193

SPRING SASH BALANCE, Filed Nov. 17, 1950 I v 2 Sheets-Sheet 2 INVENTOR.

ATTORNEYS.

Patented July 7, 1953 UNITED STATES PATENT OFFICE SPRING SASH BALANCE I Axel W. Anderberg, Los Angcles, Calif. Application November 17, 1950, Serial No. 196,320

' 7 Claims. (01. 16-197) The present invention relates generally to new and novel features of spring sash balances, and more particularly to improvements in the means for fastening and guiding the springs in sash balances.

Sash balances of this type generally comprise a housing containing a spring balance unit or two spring balance units which are duplicates of each other. Each unit includes an axle uponv which a drum is rotatably mounted. A spirally coiled spring connects the axle to the drum and the drum has wound upon it a cable which is attached to a sash. In the case of a double unit the two cables coming out of the bottom of the housing are attached one to the upper sash and one to the lower sash. The spring within each drum tends to wind up the drum and thereby exerts a pull on the cable which counterbalances the weight of the sash.

In conventional types of construction of sash balances, the drum is mounted to rotate about a fixed hub 0r axle. The drum is formed of sheet metal and ordinarily the bearing between the drum and its axle is limited to the thickness of this metal sheet from which the drum is formed. Such a narrow bearing frequently causes'extremely rapid wear of the axle and the central bearing of the rotating drum; and this condition is particularly true where one part has sharp or ragged edges which score the other part to such an extent that the central bearing for the drum becomes out of round and tilts. Eventually the drum becomes noisy and sooner or later it jams, failing to rotate. After this condition once starts, it seems to accelerate wear which continues to the point at which the drum binds, being more free to lean, and fails to function properly.

In the usual construction, the drum has a side wall or face which bears against the balance housing; and as long as this engagement is maintained the drum is held in the proper upright position to resist eccentric loading applied to it by the cable attached to the sash. However, be cause of the narrow width of the bearing between the drum and the axle the drum often times tilts on its bearing. This condition is accentuated when the bearing becomes worn as just described. The tilting of the drum not only wears the bearing at the axle but also brings the rim of the drum at the top of the opposite side in contact with the inner face of the housing. In'addition to the undesirable wear on the rim of the drum and the housing resulting from such engagement; the drag on the drum causes it to rotate unevenly in a jumpy manner.

' at one or both sides of the slot.

In addition to the annoyance caused by a sash balance that does not work smoothly and properly, the vibration setup by improper operation, combined with the flexing of the spring as it winds and unwinds, causes the end of the spring to creep slightly at the point where it is anchored to the fixed axle. In order to make-for speed and cheapness of assembly, it is not customary to provide a positive connection between the inner end of the spring and. the axle but merely to secure the parts together frictionally. This minute movement imparted to the spring from the causes described, causes the spring end to creep in a direction to disengage it from the axle and this sometimes occurs after long usage. The result is a completely inoperative sash balance which must be replaced.

It thus becomes a general object of my invention to provide an improved connection at the inner end of a sash balance spring attaching it to the axle in order to effect a positive connection between these members but one which can still be made quickly and easily.

It is also an object of my invention to provide an improved form of sash balance in which the rotating "drum is provided with a wider bearing on the stationary axle while the'spring is constructed in a manner to accommodate this wider bearing and not to reduce the efiective width of the spring.

The above and other objects and advantages of my invention have been attained by providing an improved form of sash balance in which the stationary axle being hollow is provided with a longitudinally extending slot having a recess 7 V The recess is shorter than the axial dimension of the slot and thus forms a pair of shoulders, one at each end of the recess. The drum is rotatably mounted upon the axle and a spiral spring inside the drum is connected at its outer end to the drum and at its inner end to the axle. At its inner end, the spring has 'a section of reduced width providing shoulders which engage the aforementioned shoulders on the inside of the axle when the narrow section of the spring extends out of the axle through the recess. The shoulders on the spring are preferably spaced from the end of the spring a distance equal approximately to three-fourths of the inside diameter of the axle.

The side wall of the drum is provided with an inwardly turned flange around the opening through which the axle extends, this flange providing a substantial increase in the bearing area of the drum on the axle' over the bearing afforded by the thickness'of the sheet alone; By notching the spring to a depth slightly in excess of the length of the flange, the notch serves not only to provide at one end the shoulder engaging the hub inside but as a means for clearing the drum flange and allowing the spring throughout its efiective length to be substantially the full Width of the drum. I

In a variational form of my invention, I place a sleeve around the central axle, the sleeve thickness being the same or somewhat less than the radial width of the drum flange. The sleeve may be used at any time, but is especially useful with relatively thin spiral springs in preventing abrasion of the flange by the spring. Use of the sleeve enables the notch in'the spring to be shortened as the sleeve holds the initial turn of the spring away from the axle.

How the above objects and advantages of my invention, as well as others not specifically referred to, are attained will be more. readily understood by reference to the following descrip tion and to the annexed drawings, in which:

Fig. 1 is a view showing an improved form of sash balance, consisting of two units, installed in a window casing, the view being partly in vertical median section and partly in side elevation;

Fig. 2 is a combined section and rear elevation on line 22 of Fig. 1, part of the housing being broken away to show the upper unit;

Fig. 3 is an enlarged plan View of a part of the spring at the inner end showing the shoulders which engage the axle and the notched section forming said shoulders;

Fig. 4 is an enlarged-fragmentary. perspective view of the spring at the inner end but with the spring coiled;

Fig. 5 is a perspective view of an axle detached from the housing;

Fig. 6 is a fragmentary perspective view of the axle showing the inner end of the spring attached thereto, and a cutaway section of a portion of the drum as it bears around the axle;

Fig. 7 is an enlarged fragmentary view similar to Fig. 2 showing a sleeve surrounding the axle of the upper unit;

Fig. 8 is a perspective of the sleeve alone;

Fig. 9 is a perspective similar to Fig. 6 showing a sleeve in place on an axle; and

Fig. 10 is a fragmentary median section on line Ill-l0 of Fig. '7 with some parts shown in elevation.

Referring now to the drawings, the housing of the sash balance is in two parts. One portion is a rectangular face plate I0 which is pro vided at the upper and lower ends with countersunk apertures II through which nails or screws may be passed to fasten the sash balance to window casing l2, as shown in Fig. 1. The other portion of the housing is cover l4 which is in the shape of a shallow box normally formed by a die stamping operation. The box-like cover is generally rectangular in outline and includes a fiat platelike portion I5 to which two parallel side walls l6 and two curved end walls I! are integrally connected. At the lower end, two openings I8 are provided in the cover for passage of the flexible cables 20, as will be further described. It is also preferable to cut away the lower corners of face plate ID as shown in Fig. 2 in order to eliminate any sharp bend in a cable as it leaves the balance housing and. passes down the inside surface of window frame [2. In width, cover I 4 is slightly less than the full Width of face plate I0 and fits snugly between 4 shallow longitudinal side flanges 2| at either side of the face plate l0.

Two axle members 24 are attached to face plate H3 at vertically spaced positions. These two axle members are the same in all respects; therefore only one of them is shown and described in detail. As shown particularly in Fig. 5, each axle 24 is a hollow, tubular member provided at each end with a pair ofeprojections or lugs 25 which are long enough to extend through face plate I0 or cover I4 as the case may be. The outer ends of one pair of projections 25 are upsetor flattened by any one of various procedures to fasten the axle securely to the face plate at one end. At the other end, projections 25 extend through cover l4 and are likewise upset to provide a firm. connection between the cover and axle. In this way the cover is held in placeb-y the two axles to complete the enclosure of the tWo drums and the other internal parts of the sash balance.

Axle 24 has 'a longitudinally extending slot 26 which extends for thefull length of the axle and is open at each end. At at least one side of slot 26, and preferably at both sides, is a recess 27 in the wall of the axle which is centrally disposed with respect to the length of the axle and slot 26in order to leave at each end of recess 21 a short lug 28 which is an integral portion of the axle. Although one such recess 27 is sufiicient for a single unit balance, it is preferable to provide two recesses in order that the axle is entirely symmetrical and may therefore be assembled with either end in engagement with the face plate and still properly receive the spring of either unit, as will become apparent. One or two recesses 21. produce in slot 28 an intermediate portion of increased width.

Coil spring 30 surrounds axle 24 and is contained within drum 32 which is rotatably mounted upon the axle. The outer end of spring 30 is fastened to the inside of drum 32 at 33 in any suitable manner. The connection is here 'shown as being accomplished by bending over the extremeend of the. spring to form a hooklike terminal which engages a raised tab formed integrally within the drum. The tension on the spring keeps the spring and the tab always in engagement. Any other suitable type of connection at this point may be used if desired.

The inner end of the spring is connected to axle 24, as shown particularly in Figs. 2 and 6. The spring is formed from a strip originally uniform in width throughout its entire length; but according to my invention the inner end of the spring is notched as'shown in Fig. 3. A cutaway section 34 at one side of this spring at least, and preferably at both sides as shown, is made by removing one or two narrow elongated portions of the spring lying between the dot-dash lines showing the original outline and the solid lines of Fig. 3. The end of notch 34 near the extreme inner end of the spring is squared off as shown in Fig. 3 to provide a shoulder 35 which is adjacent to but spaced a short distance D from the extreme end of the spring. With a notch 34 on each side of the spring, there are a pair of such squared shoulders 35. For reasons that will become apparent, the end of each notch 34 is so located that shoulder 35 is spaced from the end of the spring a distance less than the inside diameter of axle 24, this distance D preferably being equal to approximately threefourths the inside diameter of the axle.

an el-e3 =.Thelengthmf 'thernotchiL may vary withthe thickness sand/pr .stifiness' zoi spring 13.0, but -.in" general :it is preferably .in excess 'of the external I circumference .of :axle '24 *with' the construction shown in;1 'ig.:2; The iother' end ofzthemotchrat' 36 :may be rsquared but :is-preferably. .rrounded "as shown.

Connection of the inner :end :of ispring, 30 to axle. .24 :accomplished :easily jduringv the as-' sembly or" the "parts; .All that :is necessary .is to insert the end of the spring into the axlecthrough slot 26 andbring portion-"ma :otreduced width of :the springv out-of'ther'axle'thrcugh a recess l'l.

A pull on the spring brings;shoi1lders='35;10f the spring into engagementwith .the inside :01 the axle at lugs128. .The 'pull :of the spring-swings the terminal sectionlDcaroundtwithin the axle until the "endof :the springrengages the insidepf the "axle "at some'suchiiposition as shown in Figs. 2.;and 6. .It will beireadilyappreciated under'the' circumstances'that the; length of spring D beyond 3 shoulders 35 is made shorter than the internal diameter of axle 24 in order to fit 'withinthe axle; but an adequate clearance for the parts' without making the spring too short is bad when this distance, shown in Fig. '3, is equal to 'approximately three-fourths the internal diameter of the axle.

Each drum '32 is'cylindrical in outline and is provided atone side with an integralsidewall 38.

The other end of'the drumis openlm'aking the drum cup-like when viewed from that end. Wall 38 is provided with a centrally locatedo'pening surrounded by a short, inwardlydrawn flange 39. Axle 24 extends though this central open-- ing and is surrounded by 'fiange {39 which forms? a bearing for the drum 'eng aging the axle.

In a sash balance of this type, the'm'aximum' width of the coil'spring' is determined by-the'axial length of axle 24 since the 'two axles form spacers between face plate In and the parallel plate'fl'5 of cover l4. However, drum flange 39 covers'a' portion of slot 26 'inthe 'axleand has the effect of further reducing the width of, spring that can be used if the spring is of uniform widththroughout its length. By providing at least onenotch 34 in the side of the spring which is deep enough and long enough to clear .flange;39,,; as may be seen in Figs. 1 and 6, the. spring may be returnedto. its maximum possible width after. it .has.

cleared this flange. When no sleeve around the. axle is used as described below; the, portion of reduced width aim is typically made slightly longer than the external circumference of the. ced width of the spring is maintained for the first full turn-" The axle in order that the redu spring in the range-of .'022-'.026inch or thicker."

A spring of this type has suflicient inherent still ness that in one turn or lessthe end '36 of notch 34 is well outside the drum flange. With a medium spring, about .018'-.022' inch'thick 'asfull turn or a little more may be'requiredl 'zFor light-f er springs the situation is discussed'belowr Fig.3, shows a portion :of the spring near the inner end as it appears-when it is;-fiattened.-out

or whenlitiis:astrimbefore being coiled. After; th-ecspring :has been coiled, the same inner 1-Porappears ;as;in.Fi g.'4.-. The {initial turnis of larger. diameter-than when in the drum and consequently. 11's somewhat less than av complete circle, because the spring is shown as it appears whenifreecfrom the :tension under .which-it is placed when ther spring :is-in place withina drum LEach'offlthe ,two drums 32 has .a fcable 2-0 on it. -Qneend of the cable is connected to the drumbyrweaving it in and-out through a plurality:of;..slots 32a, or in any-other desired manner. .xA'fitermaking'three or .tour complete turns. about [the outside of the drum, the "cable passes downwardly and out of the v; ba1ance housing. The lower endof each cable qisiastenedto an T angle i clip' lewhich in turn isrfasten'ed to a sash. The .cablesare-wound on .to two drumsimsuch -a:way that' ;the drums revolve in opposite directions formovernent of the cable ina givenzdirection; thus the upper drum revolves clockwise and the lower drum counter-clockwise as cables 2i ;ar e;p.ulled down out'of the housing. .Itis desirable from a standpoint of manufacture to make as-rma-ny parts exactly alike as possible since this not only reduces the capital investment required for tooling but :also simplifies assembly operations. For this reason, axles 24, spring-s38 and drums v- 32 are all made so that they may; be used. interchangeably in both the upper orj,lower positions; and it-isfor this reason-thatzcertain openings or shapes, suchasrre cess;.2 L and .notch .34, are duplicated though only .one' is irnuse at any given time. However, :it is withinthe scopeof :my invention to provide each ceil-rsprings'iil with only asinglenotch and each a-x-le .24- with only .asingle recess .21 since'this is adequate in-.singl e'unit balances andalso permits theseparts'tobe used in the upperor the lower position .of a double unit balance accord ing tothelocation of the .notchand/or recess.

As mentioned above, the maximum possible width of .the coil spring is .the distance between the -inner.- faces;;of face plate .10 .and cover-14.

Actually the coilspring should be somewhatless than that-in order to provide adequate clearances.

Also, greater clearance is .requiredat A l between the rim of the drum and the inner face of the cover in ordergto avoid having the drum-scrape "on the-cover. An improved operation of;the

area I .which .is located concentrically with the,

drumands coil: spring. can be accomplished byembssingthe .fmain plate portion I 5 .of cover l 4 as shown-inthelowerhalf of Fig. 2. :By embossing the co-ver. to provide an. inwardly offset annular axis of axle 24, this embossed area of the plate beargelightlyagainst .one ;side of coil sprin 30. In; practice theembossment is deep enough to ()Q i provide a -maximumclearance between the spring and therembossedsareapn'the cover oiabout .010

inch; butcin wactual practice the spring. bears againstrtheplate lightly'since the spring is. other- Wisafree-to mover-away fromside-plate 38. The

embossed. area cooperates with sideplate ,38' sof the drum .to confine and guide the spring as iit coilganduncoils. Furthermore the .light pressure imparted to the spring is transmitted to drumplatefi 8. which tendsto offset .the eccentric loadingimparted to thedrumb'y thepull on cable 2l ...,,Thispressure entire-spring tends to keepithe drum in a properly upright position-and to maintain adequate clearance at -44 bet-ween .the cover andttheadjoininglrim onthedrum.

jpositeveach drum 32,: the plat iisemhessed'to Whemit isfdesired to produce a sash balance witha comparatively light pull, this is generally accomplished by using a thinner spring, since for rea s'ons pointed'out above it is desirable that the Width of the spring be maintained constantasareall other dimensions" of the balance. To make'such a sash balance, it may be desiredto use a spring which is relatively thin or light, for cxamplene'a'r or within the range of .014-0.18 inch thick which'is only approximately one-half the radial thickness of drum flange 39.

A thin spring or this characteris easily flexed and its'norm'al pull is sufficient to wrap it on axle 2 5 for about one to two complete turns. Whenthisis the case, notch 34 must be made quite long, as for example two or more times the circumference of axle 24, in order that the rounded shoulder 36 at the end of the notch may certainly be completely outside the flange on the drum. Otherwise this rounded shoulder rides on the flange with'resultant jumpy uneven motion of the balance unitand eventual scraping away of a large portion of the flange.

I have found that this condition can very easily be'eli'minated by the addition to the structure previously described of annular sleeve 45, shown .in'Fig.;8. The internal diameter of this sleeve is very slightly larger than the external diameter of axle 24 so that the sleeve fits over the axle with a loose slidin fit. Sleeve ifi has a single longitudinally extending slot 46 which permits the sprihgtt i pass outwardly'through the sleeve, as may be seen in Fig. 7. The slot in the sleeve does not line up with slot 26 inthe axle since the pullof the spring is sufiicient to rotate the sleeve about the axle to some such position as shown in'Figs. 7 and 9 in which the sleeve more or less covers axle slot 25, depending upon the relative widths of these two slots. It will be seen that theaction of the sleeve in covering slot 26 acts as a further safeguard to insure that the end of thespring is positively locked inside the axle and cannot come out.

-In Figs. '7, 9 and 10, sleeve G5 is shownas having the same wall thickness as drum flange 39,

but my invention is not necessarily limited to this or any other specific thickness for the sleeve. A thickness equal to the flange is probably the maximum useful thickness, since a thicker sleeve may be used but no added advantage is derived from the increased thickness. On the other hand, the minimum thickness of the sleeve depends somewhat-upon the thickness of the spring since it is desirable "that the sleeve plus one turn of the spring have a combined thickness equal to or greater thanithe radial thickness of flange 39 on thedrilni. 'Thes'leeve wall may have any desired thickness in between these two limits which permit a subs'tantial range of sizes.

The spring initially wraps around the outside of the sleeve, rather than the axle itself as in Fig. 6. The larger diameter causes spring shoulder 36 to be farther out from the axis of the drum than it would be Without the sleeve, other things remaining the same;- and the net result is that the length L-of notch 34 may be shortened.

' Undei the conditions illustrated wherein the sleeve wall is the same thickness as the drum flange, the spring is initially spaced far enough outwardly from the axle that it doesnot engage the drum flange,almostwithout reference to'the 7 Of course under these conditions the minimum length of the notch 34- length of notches 34.

necessary: "because I substantial variations are excess of the external circumference of the sleeve.

is satisfactory even though the spring lies in contact with the'sleeve for'one completeturn since that turn adds to the'eifective thickness of the sleeve; As either th sleeve is made thicker or the spring is made thicker'and therefore becomes stiffer so that it lies incontact with the sleeve for a shorter portion of the total circumference,

the length of the notch maybe decreased accordingly; Thedesirability of a relatively thick sleeve to offset the high'fiexibility of a relatively thin spring can be seen from Figs. '7, 9 and 10 in which the spring is illustrated as if it were sufiiciently thin and vlimber that it lies in contact with the'sleeve and then with the first turn of the spring for a totalof about one and one quarteror moreturns. Without a sleeve v45, the

dimension L of the notch would necessarily be about. two or more times" the external circum ference of. axle Has one turn is required'in lieu of the sleeve; but withthesleeve shown the notch length inthe same spring may be safely decreased to slightly inexcess of one circumference. Intheory at least, a still shorter notch may be used butit is undesirabl in practice because of the small'clearance created by so thin a sprin Having described and illustrated a preferred form of my invention, and indicated certain modifications thereof, it will be understood that various changes in my improved sash balance may be made by persons'skilled in the art without departing from the spirit and scope of my invention. For example, it will be understood from the abov description that various changes in the sizes and proportions of the parts may be madeflConsequently l wish the foregoing disclosure to be considered as illustrative. of, than flimitative upon, the appended claims Iclaim: r

1. in a spring; sash, balance, the combination comprising: a, stationary axle, the axle being hollow and having a' longitudinally extending slot at oneside, the slothaving an intermediate portion of increased width; and a spiral spring connected at its inner end to the axle, the spring near its inner end havinga section of reduced width providing ashoulder engaging the inside of theaxle at one side of theslot with the narrather 9 in the spring of reduced width is at least as long as the circumference of the axle.

4. In a spring sash balance, the combination comprising: a stationary axle, the axle being hollow and having a longitudinally extending slot at one side, the slot having an intermediate section of increased width; and a spiral spring connected at its inner end to the axle, the spring near its inner end having a section of reduced width providing a shoulder engaging the inside of the axle at one side of the slot with the narrowed portion of the spring extending out of the axle through the intermediate portion of the slot; and a sleeve loosely mounted on .the axle spacing the initial turn of the spring from'the axle and having a longitudinally extending slot through which the narrowed portion of the spring passes.

5. In a spring sash balance, a combination comprising: a stationary axle, the axle being hollow and having a longitudinally extending slot at one side, the slot having an intermediate section of increased width; a drum rotatable about the axle and provided with a wall at one side a portion of which is drawn inwardly and axially to form a bearing flange around a central opening through which the axle extends to rotatably support the drum; and a spiral spring connected at its outer end to the drum and at its inner end to the axle, the inner end of the spring having a notch at each sid forming a pair of shoulders closely spaced from the end of the spring and located at each sid of a central narrowed portion of the spring, the shoulders having a depth slightly in excess of the length of the drum flange measured parallel to the axis of the drum and engaging the inside of the axle when the narrowed portion of spring extends out of the axle through the intermediate portion of the slot, the spring for the major portion of its length having a width substantially equal to the inside depth of the drum.

6. In a spring sash balance, the combination comprising: a hollow stationary axle having a longitudinally extending slot in one side, the slot having an intermediate portion of increased 10 width; a drum rotatable about the axle and having a wall at one side a portion of which is drawn axially of the drum to form a bearing flange around a central opening through which the axle extends; and a spiral spring connected at its outer end to the drum and at its inner end to the axle, th spring near its inner end having a section of reduced width providing a shoulder engaging the inside of the axle with the narrowed portion of the spring extending out of the axle through the intermediate portion of the slot, the depth of the shoulder being in excess of the length of the drum flange measured parallel to the axis of the drum.

7. In a spring sash balance, the combination comprising: a hollow stationary axle having at one side a longitudinally extending slot that has an intermediate section of increased width; a drum rotatable about the axle and having a wall at one side a portion of which is drawn axially to form a bearing flange around a central opening and around the axle; a spiral spring connected at on end to the drum and at the other end to the axle, the spring having near its inner end a section of reduced width providing a shoulder engaging the inside of the axle with the narrowed portion of the spring extending outwardly of the axle through the intermediate portion of the slot; and anannular sleeve loosely mounted on the axle and spacing the initial turn of the spring from the axle, said sleeve having a longitudinally extending slot through which the narrowed portion of the spring passes and the thickness of the sleeve wall being substantially equal to the thickness of the drum flange.

AXEL W. ANDERBERG.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,430,138 Wread Y Sept. 26, 1922 1,898,58 Mantz Feb. 21, 1933 2,242,650 Mantz May 20, 1941 2,534,968

Haas Dec. 19, 1950 

